1. Field of the Invention
The present invention relates to optical circuits and optical circuit devices applied to telecommunication fields and the like, methods of manufacturing the optical circuit and the optical circuits devices, and methods of controlling the optical circuit devices.
2. Description of the Related Art
Optical circuits applied to optical communications and the like generally have a silicon substrate and an optical waveguide layer formed on the silicon substrate; the optical waveguide layer has a core and a cladding. Optical circuits can be formed into optical circuit devices having various functions by setting the optical waveguide configuration (core pattern) formed by the core in a variety of ways.
An example of such optical circuit devices is an optical circuit device having a Mach-Zehnder interferometer circuit 30 as shown in FIG. 1-16.
In addition, an optical circuit device having a cross-sectional configuration as shown in FIG. 1-18 has been proposed (see, for example, Yasuyuki Inoue, et al. “Polarization Sensitivity of a Silica Waveguide Thermooptic Phase Shifter for Planar Light wave Circuit”, IEEE Photonics Technology Letters, vol.4, No. 1, January 1992, p.36).
Furthermore, optical circuit devices as shown in FIGS. 1-19 and FIG. 1-20 have also been proposed (see, for example, Akio Sugita, et al. “Bridge-Suspended Silica-Waveguide Thermo-Optic Phase Shifter and Its Application to Mach-Zehnder Type Optical Switch”, The Transaction of the IEICE, Vol. E73, No. 1, January, 1990, p.105).
Still further, another example of optical circuit device is an optical circuit device having a Mach-Zehnder interferometer circuit 30 as shown in FIG. 2-13-A.
As further another example of optical circuit device, an optical circuit device having a configuration as shown in FIG. 2-15 has been proposed (see, for example, Hashizume et al. “Reduction in PDL of PLC-type variable optical attenuator” General Conference of the Institute of Electronics, Information and Communication Engineers, 2001, C-3-64).